Taco Bell claims that its product developers came up with the idea for the Doritos Locos Taco -- probably the most successful new fast food item of the 21st century so far, with more than half a billion sold in the past 14 months -- at a summit with Frito-Lay executives at its Irvine, Calif., headquarters.

But a lawsuit filed by federal prison inmate Gary Cole in the U.S. District Court for the Northern District of Texas on May 15 alleges that the story behind the taco is a lie. In his 35-page handwritten complaint, Cole insists that he invented the Doritos Locos Taco -- and that Taco Bell and Frito-Lay stole the idea from him through the mail.

In September 2006, Cole wrote up a list of nine product ideas. Most of them were assorted products -- hot sauces, body oils, health mixes -- to be sold under the brand "Divas and Ballers." But one, the second in the list, was "Taco Shells of All Flavors (Made of Doritos)."

The complaint says Cole sent the list to Janice B Cole and Keoiana K. Cole in September 2010 -- but that the letter was "stolen through the United States Postal Service Mail and submitted to Frito Lays [sic], Taco Bell, Pepsi Co, Yum Brands," by someone whose identity remains a mystery to Cole. The companies gave the mail thief "a check ... for a large amount" for the rights to his idea, then started manufacturing and selling the Doritos Locos Taco, the complaint says. It is unclear how Janice and Keoiana Cole are connected to Gary Cole.

Taco Bell responded to questions from The Huffington Post about the complaint with an emailed statement. "We have not been served with the lawsuit, but the claims we’ve read in online news sources are completely false and without merit," it said.

In his lawsuit, Cole asks the court to order Taco Bell, Frito-Lay, PepsiCo and Yum Brands to give him documents regarding the invention of Doritos Locos Tacos, which he is confident will prove that they stole the idea from him. In the meantime, he requests that the court place "a lien on Taco Bell, Frito Lays, Pepsi Co, Yum Brands, to stop the production and sell of taco shells made of Doritos flavors."